GCN Circular 11111

C. B. Markwardt (GSFC/UMD), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
S. R. Oates (UCL-MSSL), D. M. Palmer (LANL), A. M. Parsons (GSFC),
T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):

Using the data set from T-119 to T+263 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 100816A (trigger #431764)
(Oates, et al., GCN Circ. 11102
Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 351.738, 26.568 deg which is
    RA(J2000)  =  23h 26m 57.1s
    Dec(J2000) = +26d 34' 04.4"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 33%.

The mask-weighted light curve shows a single symmetric peak. There is
low-level ongoing emission out to about T+100 sec.  T90 (15-350 keV) is
2.9 +- 0.6 sec (estimated error including systematics).

The time-averaged spectrum from T-0.7 to T+4.5 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.73 +- 0.24,
and Epeak of 170.7 +- 79.7 keV (chi squared 50.79 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 2.0 +- 0.1 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T+0.10 sec in the 15-150 keV band is
10.9 +- 0.4 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.16 +- 0.06 (chi squared 61.72 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/431764/BA/